JP-2005-048706A shows a valve timing controller which includes a guide rotation member provided with guide grooves, a plurality of movable bodies sliding in the guide grooves, and a bearing rotation member radially supporting the guide rotation member. A plurality of link mechanisms connects the moveable bodies with the guide rotation member. Since each element in a motion transfer system from the guide rotation member to the bearing rotation member constructs a constrained chain, operational conditions of each element are defined according to its valve timing.
Between the guide rotation member and the bearing rotation member, a radial clearance gap is formed to permit a relative rotation. A radial displacement may be arouse due to a manufacturing tolerance between the guide rotation member and the bearing rotation member. In a case that the clearance gap is excessively small, each rotation member collides with each other, so that the guide rotation member may stick on the bearing rotation member, and an operation lock and a reduction in strength may be arouse. Besides, a clearance gap is formed in width direction between an inner surface of the guide groove and the movable member. Even if one of the movable bodies is engaged with the guide groove, the other movable body may not be engaged with the guide groove. In this case, operation load is concentrated on the movable members or the link mechanisms, which may cause a reduction in strength.